As an air conditioning device utilized in a structure such as a building or a general residence, a separate type air conditioning device including an indoor unit and an outdoor unit is widely used. In the outdoor unit of the separate type air conditioning device, for example, as described in Patent Literature 1 to be described below, various devices such as a compressor and a heat exchanger are accommodated inside a casing. The casing of the outdoor unit includes a bottom plate on which various devices are mounted, a plurality of support pillars standing on this bottom plate, a top plate coupled to upper ends of the support pillars, and side surface panels for closing openings between the support pillars.